Method of automatically repairing cracks and apparatus for use in such method

ABSTRACT

The invention provides a method and apparatus for automatically repairing the cracks produced in the member to be repaired. A wide field image is obtained by photographing the whole surface of a blade  31  or the like in a wide field view by a remote camera  11  and the position of cracks on the surface of the blade is obtained as a rough position information of the cracks by processing the image of wide field view. Then, the cracks are photographed in a narrow field view at the predetermined spacing along the cracks based on the rough position information by light section method. The narrow field images are processed to obtain the position, width, and depth of the crack at each predetermined spacing, which compose crack data at-the series of points, and the cracks are repaired based on the crack data at the series of points.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of repairingautomatically the cracks in a member to be repaired and an apparatus foruse in such a method, specifically a method of repairing automaticallythe cracks produced in the blade, etc. of a rotary machine and anapparatus for use in such a method.

[0003] 2. Description of the Related Art

[0004] Generally, cracks tend to occur in a blade, etc. of a rotarymachine (for example in a turbine blade) owing to the severe environmentof operation. Therefore, it is required in the operation of a turbine,etc. to periodically check if a crack is produced or not. To beconcrete, the blades are checked after the operation of the turbine, andif a crack is found, the crack is repaired.

[0005] Recently, apparatuses for automatic welding have been developed.Welding can be carried out automatically by the use of such an automaticwelding apparatus. However, in the case of repairing cracks, the statesof cracks are diverse and it is difficult to repair the cracks by usingan automatic welding apparatus. To be more specific, when repairingcracks by welding, the welding must be performed according to thedirection, position, depth, etc. of the cracks, so the repair of cracksby an automatic welding apparatus has been difficult. Therefore, therepair of the crack produced in the blade, etc. has been carried out byhandwork, in which the position, width, depth, etc. of the crack arerecognized by hand, the aperture of the crack is ground, then the groundportion is welded by hand welding.

[0006] When the crack has been repaired, as has been described above, byhandwork, recognizing by hand the position, width, depth, etc., grindingthe aperture of the crack, then welding the ground part by hand welding,proficiency has been required in repairing, and in addition, thegrinding and welding should have been carried out according to theresult of careful examination of the crack for repairing the crackproduced in a member to be repaired such as a blade, etc. Therefore,when considering the diversity of the states of cracks, the number ofprocesses increases inevitably for repairing the crack produced in amember to be repaired such as a blade, etc.

[0007] Further, since skill is required for repairing cracks asmentioned above, the result of repair is dependent on the skill of awelder, so there occurs the problem that stable quality of the repairedpart is not assured.

[0008] To overcome the disadvantage mentioned above, an invention wasdisclosed in Japanese Patent Application Publication No.9-145340, forexample, for reducing man-hours required to detect and measure cracks atthe inspection or for automatization of these steps concerning gasturbine blades.

[0009] According to the disclosure, the apparatus is composed of, asshown in FIG. 7(A), a detector (camera) 121 to detect cracks, a driver122 to drive the detector, a position controller 123 to control theposition of the driver, an image processing apparatus 124 to process theimage information of the surface of a stator vane input from thedetector, a calculation operation unit 125 to determine the degree ofdamage such as the maximum crack length, sum of crack lengths, etc. bymeasuring crack lengths from the processed image, and a memory 126 tostore the data of the shapes of stator vanes. With the apparatus, thedetected image of a crack is divided properly, the coordinates of eachpoint of division c1, c2, c3, . . . are projected on the real shapemodel to determine the real crack length, as shown in FIG. 7(B).

[0010] However, in the art mentioned above, the measurement in the caseof a branched crack is not taken into consideration. Further, whenprojected in a wide field of vision, the depth of the crack can not bedetermined, and when projected in a narrow field of vision, the path ofthe crack can not be judged. As a result, the accuracy of determinationof cracks decreases.

SUMMARY OF THE INVENTION

[0011] The objective of the present invention is to provide a method ofautomatically repairing cracks and an apparatus for use in such amethod, by which the crack produced in a member to be repaired, etc. canbe automatically repaired with good accuracy.

[0012] According to the present invention, a method of automaticallyrepairing cracks having a first step for obtaining as the rough positioninformation on the cracks, which is the information of the presence andabsence of cracks and the position thereof, by processing the wide fieldimage obtained by taking the picture of the member to be repaired in awide field of view; and a second step for obtaining the crack data at aseries of points along the cracks, which is the information of theposition, width, and depth of the cracks at each point having a spacingpredetermined along the cracks and is determined by processing thenarrow field image of the cracks photographed at each point spaced bythe predetermined spacing based on said rough position information; isprovided.

[0013] After the crack data at the series of points is obtained, thecracks are repaired according to the crack data at the series of points.For example, first, the cracks are ground according to the crack data atthe series of points, then the cracks are welded according to the crackdata at the series of points. Light section method is used to obtainsaid crack data at the series of points. Said predetermined spacing is adistance between adjacent points of photographing and the distance isdetermined in the range so that the line segment connecting saidadjacent points of photographing can be assumed as a straight-linesegment.

[0014] As the repair of the cracks is done by obtaining the crack dataat the series of points by image processing thereof and repairing thecracks according to the crack data at the series of points, automaticrepair of cracks is possible.

[0015] Further, according to the present invention, the automaticrepairing apparatus used in repairing the cracks produced in said memberto be repaired, is provided with a first photographing means to take thepicture of said member to be repaired in a wide field view in order toobtain the wide field image thereof; an image processing means to obtainthe rough position information of the cracks, which is the informationof the presence and absence of cracks and the position thereof in saidmember to be repaired, by processing said wide field image; and a secondphotographing means to obtain a narrow field image of the cracks byphotographing the cracks at each point having a spacing predeterminedbased on said rough position information in a narrow field view, andsaid processing means processes said narrow field image to obtain thecrack data at the series of points, which is the information of theposition, width, and depth of the cracks at each point spaced by apredetermined distance, by processing said narrow field image.

[0016] After the crack data at the series of points is obtained, thecracks are ground according to the crack data at the series of points,then the cracks are welded according to the crack data at the series ofpoints. Light section method is used to obtain said crack data at theseries of points.

[0017] Light section method in the field of welding is well known. Asdisclosed in Japanese Patent Application Publication No.6-344144, inFIG. 6, reference numeral 101 is a welding torch, 102 is a CCD camera,103 is a laser slit light source slanted by determined angles withregard to the CCD camera 102, 104 is a laser slit light emitted from thelight source 103, 105 is a groove face, 106 is an image processingapparatus, 107 is a monitor, 108 is a welding electrode, 110 is awelding wire, 112 is welded beads, and 114 is a interference filter. Thelaser slit light 104 which is a laser light flux emitting through a slitirradiates the groove face 105 at a right angle to the weld line. Thelight section image obtained in accordance with the groove shape isreceived by the camera via the interference filter which passes thelight of the same wavelength as the laser light. The shape of the grooveis determined by processing the image received by the CCD camera by theimage processing apparatus 106. For example, the laser split light ofwavelengths of 600-800 nm is emitted intermittently at an interval of ashort time, and image processing is performed to take out the imagecontaining only the laser slit light by detracting the image notcontaining the laser slit light from that containing the laser slitlight or by taking an exclusive OR of both images.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a block diagram showing an example of the control systemof the apparatus for automatically repairing cracks according to thepresent invention.

[0019]FIG. 2 is an example of the driving mechanism of the apparatus forautomatically repairing cracks according to the present invention.

[0020]FIG. 3 is an illustration showing the relation of the positionsbetween the mounting stage rotating body and mounting stage incliningbody.

[0021]FIG. 4 is an illustration showing the position of taking thepicture of a crack.

[0022]FIG. 5(A) is an illustration showing the welding of the startpoint of the crack, FIG. 5(B) is an illustration showing the welding ofthe first midpoint of the crack, FIG. 5(C) is an illustration showingthe welding of the second midpoint of the crack, and FIG. 5(D) is anillustration showing the welding of the endpoint of the crack.

[0023]FIG. 6 is a schematic representation of light section method inthe field of welding.

[0024]FIG. 7(A) is a block diagram of a crack repairing apparatus of theprior art, and FIG. 7(B) is a block diagram showing the procedure ofdetermining real length from the length of the projected image.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] A preferred embodiment of the present invention will now bedetailed with reference to the accompanying drawings. It is intended,however, that unless particularly specified, dimensions, materials,relative positions and so forth of the constituent parts in theembodiments shall be interpreted as illustrative only not as limitativeof the scope of the present invention.

[0026] The present invention will now be explained hereunder by takingas an example the case of repairing the crack produced in a turbineblade, however, the present invention can be applied similarly to thecase of repairing a member (member to be repaired) other than a turbineblade.

[0027] Referring to FIG. 1, the automatic crack repairing apparatus isprovided with a remote camera 11, a laser slit light emitting section(laser slit sensor) 12, a CCD camera 13, a camera controller 14, aservomotor controller 15, an image procesing apparatus 16, a totalcontroller 17, an input device 17 a, a memory 18, a welding machine 19,a grinder controller 20. When grinding is carried out, the totalcontroller 17 controls grinding head (for example, pencil type grindinghead, not shown in the drawing) via the grinder controller 20. On theother hand, when welding is performed, the total controller 17 controlsthe welding head(not shown in FIG. 1) via the welding machine 19.

[0028] Referring to FIG. 2, welding torch 21 is controlled, as describedlater, by the welding machine 19 via the total controller 17. Thewelding torch 21 is mounted to a transfer apparatus 22 and manipulatedby the total controller 17 to move in three direction of X,Y,Z includingweaving motion via the servomotor controller 15.

[0029] A wire supplier 23 is provided near the welding torch 21. Whenwelding is carried out, welding wire is supplied to the top end part ofthe welding torch 21 by the wire supplier 23. The laser slit lightemitting section 12 emits laser slit light (laser light passing througha slit) onto the crack in the blade so that the light crosses theaperture of the crack. The CCD camera 13 receives the laser slit lightin the direction inclined by a determined angle against the radiatingdirection to grasp the section of the aperture of the crack by lightsection method, and the received light is sent to the camera controller14. The laser slit light emitting section 12 is attached to the transferapparatus 22 together with the CCD camera 13.

[0030] The transfer apparatus 22 is framed on a platform 221 as shown inFIG. 2. A pair of support members 22 a is mounted on the platform 221 ata determined distance. A X-direction supporter 22 b extending in adetermined direction (X-direction) is laid over the pair of supportmembers 22 a.

[0031] A Y-direction supporter 22 c extending in a direction at a rightangle to the X-direction supporter 22 b is mounted movable inX-direction to the X-direction supporter 22 b, the Y-direction supporter22 c itself is movable in Y-direction on the X-direction supporter 22 b.

[0032] In the example of FIG. 2, an end of the Y-direction supporter 22c is branched in T-shape. To an end side of the T-shaped part isattached the first Z-direction supporter 22 d, and to the other end sideof the T-shaped part is attached the second Z-direction supporter 22 e.The first and second Z-direction supporters 22 d and 22 e are movable inthe direction at a right angle to both X-direction supporter 22 b andY-direction supporter 22 c (Z-direction).

[0033] Said laser slit light emitting section 12 and CCD camera 13 areattached to the first Z-direction supporter 22 d via a rotating body 22f, and said welding torch 21 is attached to the second Z-directionsupporter 22 e via a torch rotating member 22 g and a torch weavingmember 22 h. Further, a mounting base 24 having a mounting stage 24 afor placing the member to be repaired (blade) is mounted on the platform221. A stage rotating body 24 b and a stage inclining body 24 c areprovided to the mounting base 24, and the mounting stage 24 a is drivenin three axial direction by the stage rotating body 24 b and stageinclining body 24 c, as described later.

[0034] Next, the working of the automatic crack repairing apparatuscomposed as described above will be explained.

[0035] First, the blade 31, the member to be repaired, is placed on themounting stage 24 a. The position relation among the blade 31, saidrotating body 24 b, and inclining body 24 c is as shown in FIG. 3. Then,the position, direction, width, and depth of the crack in the blade 31are recognized. To be concrete, three-dimensional information of each ofa plurality of members to be repaired is stored in the memory 18, andthe total controller 17 reads the concerned three-dimensionalinformation from the memory according to the blade selection commandgiven from the input device 17 a to recognize the three-dimensionalimage of the concerned blade from the memory 18.

[0036] The total controller 17 allows the remote camera 11 to take apicture of the whole of the blade 31 via the camera controller 14. Theentire image of the blade 31 is sent to the image processing apparatus16, which recognize the presence or absence of cracks and branch points,and their rough positions by shading. The rough position(three-dimensioncoordinates) of a crack is determined by interpolation based on theinformation of said entire image. That is, the crack informationincluding the presence or absence of cracks and branch points and theirrough positions (including its direction) are obtained in the imageprocessing apparatus 16 based on the picture taken by the remote camera11. The crack information is given to the total control apparatus 17.

[0037] After the rough position of the crack is determined, the totalcontroller 17 allows the Y-direction supporter 22 c to be moved in thedirection of X and Y by a servomotor (not shown in the drawing) via theservomotor controller 15 to position the first Z-direction supporter 22d above the mounting stage 24 a (the position of the mounting stage 24 ais predetermined).

[0038] Further, the total controller 17 allows the first Z-directionsupporter 22 d to be fine-adjusted in the three axis direction via theservomotor controller 15 based on said rough position of the crack, andthe camera controller 14 allows the camera rotating body 22 f to berotated so that the laser slit light emitting section 12 and CCD camera13 are positioned to the determined position in relation to the startpoint of the crack. That is, laser slit light emitting section 12 ispositioned so that the laser slit light crosses the aperture of thecrack and the CCD camera 13 is positioned so that it receives the laserslit light in the direction inclined by a determined angle from thelaser slit light.

[0039] Then, the total controller 17 allows the laser slit light to beemitted from the laser slit light emitting section 12 via the cameracontroller 14, the laser slit light is received by CCD camera 13. Thereceived light is given from the CCD camera 13 to the image processingapparatus 16 via the camera controller 14 as a crack image. As the imagetaken by the CCD camera 13 is an image taken by light section method,the depth of the crack can be recognized from said image of the crack inthe image processing apparatus 16. Thus, the width, depth, and position(coordinates) of the start point of the crack (hereafter referred to asthe start point data of the crack) is determined from the image taken bythe CCD camera 13 in the image processing apparatus 16.

[0040] Then, the total controller 17 controls the first Z-directionsupporter 22 d and camera rotating body 22 f to move the laser slitlight emitting section 12 and CCD camera 13 by the predetermineddistance (spacing) according to the information of rough position of thecrack (this new position is called the first midpoint). The picture ofthe crack is taken at the first midpoint by light section method todetermine the width, depth, and position (coordinates) of the crack atthe first midpoint (hereafter referred to as the first midpoint data ofthe crack).

[0041] Thus, the width, depth, and position (coordinates) of the crackare determined successively by moving the laser slit light emittingsection 12 and CCD camera 13 and taking the picture of the crack bylight section method by the predetermined distance according to theinformation of rough position of the crack. When the laser slit lightemitting section 12 and CCD camera 13 are moved to the n^(th) midpoint,the width, depth, and the position (coordinates) at n^(th) midpoint onthe crack are determined(n is an integer between 1 and N, N is aninteger equal to or larger than 1). The determination of a crack isfinished when the width, depth, and coordinates of the end point of thecrack are determined (hereafter referred to as the end point data of thecrack).

[0042] When the crack has a branch point B1 as shown in FIG. 4, thedetermination of crack is again carried out starting from the branchpoint B1 to the end point B2 of the branch (this is shown by the solidarrow line in the drawing), which is recognized as a crack.

[0043] On the other hand, the picture of the other branch of the crackis taken starting from the start point B3 to the end point B4 of thebranch to be recognized as another crack (this is shown by the brokenarrow line in the drawing).

[0044] The information of the cracks at the start points, at n^(th)midpoint, and at the end points are given to the total controller 17,which allows the memory 18 to store the information at each point as acrack data at the series of points.

[0045] After crack data at the series of points for all cracks in theblade 31 are determined, grinding is carried out for each crack. Thegrinding is performed based on to the crack data at the series of pointsstored in the memory 18. The direction of the straight-line segmentconnecting adjacent points is determined in the total controller 17. Thegrinding controller 20 is controlled to allow, for example, a penciltype grinding head (not shown in the drawing) to grind the cracks alongthe crack data at the series of points according to the predeterminedgrinding procedure. The grinding head is attached, for example, to thesecond Z-direction supporter 22 e, which is controlled to move thegrinding head according to the crack data at the series of points inorder to grind the cracks.

[0046] After the grinding of the cracks is over, then the welding of thecracks is carried out. The grinding is done for every point of theseries of points in the way the grinding head is directed at rightangles with each straight-line segment.

[0047] When welding, the welding torch 21 and wire supplier 23 arecontrolled also according to the crack data at the series of points.

[0048] It is supposed in FIG. 5 that a crack data at the series ofpoints is composed of a start point, a first midpoint, a secondmidpoint, and an endpoint. First, the head (torch head) 21 a of thewelding torch 21 is directed at a right angle to the straight-linesegment at the start point and welding is done for the start point asshown in FIG. 5(A). Welding is done similarly for the first midpoint A2,second midpoint A3, and end point A4 as shown in FIG. 5(B)˜FIG. 5(D)respectively according to the crack data at the series of points.So-called multi-layer welding is done depending on the width and depthof the crack. That is to say, welding is done according to eachdetermined depth, and multi-layer welding is done at the point at whichthe crack is deep.

[0049] In the above description, the remote camera 11 is used to takethe picture of the whole surface of the blade 31, however, one cameramay be used to take the picture of the whole surface of the blade 31 andto take pictures by light section method. In this case, a camera havingzoom lens, etc. is used, and picture taking can be done with wide andnarrow fields of view. Photographing by light section method is donewith a narrow field of view.

[0050] So-called shade photographing may be used instead of lightsection method. In this case, height sensor or the like is used, for thedepth of crack can not be determined although the position and width ofthe crack can be determined by the shade photographing.

[0051] When photographing the crack in a narrow field view, the spacingbetween each point from the start point through n^(th) midpoint to endpoint is determined so that it can be assumed as a straight line. Bydetermining the spacing like this, the welding along the crack can becarried out easily.

[0052] As has been described in the forgoing, according to the presentinvention, when repairing the cracks produced in a member to be repairedsuch as a blade, the position of the cracks is obtained as a roughposition information from the picture of the whole surface of the memberto be repaired taken in a wide field view, then the crack isphotographed in a narrow field view at the predetermined spacing alongthe crack based on the rough position information to obtain theposition, width, and depth of the crack at each predetermined spacing,which compose crack data at the series of points , and the crack isrepaired based on the crack data at the series of points.

[0053] Therefore, the invention brings about the effect that the cracksproduced in the member to be repaired can be automatically repaired withgood accuracy.

1. A method of automatically repairing cracks having a first step forobtaining the rough position information on the cracks, which is theinformation of the presence and absence of cracks and the positionthereof, by processing the wide field image obtained by taking thepicture of the member to be repaired in a wide field of view, and asecond step for obtaining the crack data at a series of points along thecracks, which is the information of the position, width, and depth ofthe cracks at each point having a spacing predetermined along the cracksand is determined by processing the narrow field image of the cracksphotographed at each point spaced by the predetermined spacing based onsaid rough position information.
 2. The method of automaticallyrepairing cracks according to claim 1, wherein a third step forrepairing said cracks according to said crack data at the series ofpoints is provided.
 3. The method of automatically repairing cracksaccording to claim 2, wherein said third step includes a fourth step forgrinding said cracks based on said crack data at the series of points,and a fifth step for welding said cracks based on said crack informationof the series of points.
 4. The method of automatically repairing cracksaccording to claim 1, wherein said crack data at the series of points isobtained by light section method in said second.
 5. The method ofautomatically repairing cracks according to claim 1, wherein saidpredetermined spacing is a distance between adjacent points ofphotographing and the distance is determined in the range so that theline segment connecting said adjacent points of photographing can beassumed as a straight-line segment.
 6. An automatic repairing apparatusused in repairing the cracks produced in said member to be repairedprovided with a first photographing means to take the picture of saidmember to be repaired in a wide field view in order to obtain the widefield image thereof, an image processing means to obtain the roughposition information of the cracks, which is the information of thepresence and absence of cracks and the position thereof in said memberto be repaired, by processing said wide field image, and a secondphotographing means to obtain a narrow field image of the cracks byphotographing the cracks at each point having a spacing predeterminedbased on said rough position information in a narrow field view, andsaid image processing means processes said narrow field image to obtainthe crack data at the series of points, which is the information of theposition, width, and depth of the cracks at each point spaced by apredetermined distance, by processing said narrow field image.
 7. Theautomatic repairing apparatus according to claim 6, wherein a repairingmeans is provided to carry out the repair of said cracks based on saidcrack data at the series of points.
 8. The automatic repairing apparatusaccording to claim 6, wherein said second photographing meansphotographs said cracks according to light section method.